Quenching dynamics in CdSe nanoparticles: surface-induced defects upon dilution

International audienceWe have analyzed the decays of the fluorescence of colloidal CdSe quantum dots (QDs) suspensions during dilution and titration by the ligands. A ligand shell made of a combination of trioctylphosphine (TOP), oleylamine (OA), and stearic acid (SA) stabilizes the as-synthesized QDs. The composition of the shell was analyzed and quantified using high resolution liquid state 1H nuclear magnetic resonance (NMR) spectroscopy. A quenching of the fluorescence of the QDs is observed upon removal of the ligands by diluting the stock solution of the QDs. The fluorescence is restored by the addition of TOP. We analyze the results by assuming a binomial distribution of quenchers among the QDs and predict a linear trend in the time-resolved fluorescence decays. We have used a nonparametric analysis to show that for our QDs, 3.0 0.1 quenching sites per QD on average are revealed by the removal of TOP. We moreover show that the quenching rates of the quenching sites add up. The decay per quenching site can be compared with the decay at saturation of the dilution effect. This provides a value of 2.88 0.02 for the number of quenchers per QD. We extract the quenching dynamics of one site. It appears to be a process with a distribution of rates that does not involve the ligands

A Drosophila-centric view of protein tyrosine phosphatases

AbstractMost of our knowledge on protein tyrosine phosphatases (PTPs) is derived from human pathologies and mouse knockout models. These models largely correlate well with human disease phenotypes, but can be ambiguous due to compensatory mechanisms introduced by paralogous genes. Here we present the analysis of the PTP complement of the fruit fly and the complementary view that PTP studies in Drosophila will accelerate our understanding of PTPs in physiological and pathological conditions. With only 44 PTP genes, Drosophila represents a streamlined version of the human complement. Our integrated analysis places the Drosophila PTPs into evolutionary and functional contexts, thereby providing a platform for the exploitation of the fly for PTP research and the transfer of knowledge onto other model systems

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

ANALYSE STRUCTURALE DES LIGNINES PAR RESONANCE MAGNETIQUE NUCLEAIRE : UTILISATION DES NOUVELLES SEQUENCES IMPULSIONNELLES ET ETUDE DES LIGNINES EXTRAITES DE BOIS TRAITE PAR AUTOHYROLYSE RAPIDE

Structural changes of lignins extracted from wood treated by flash hydorlysis were mainly established by high-resolution liquid-state 13C NMR.Quantitative NMR, 2D INADEQUATE and DEPT experiments appeared as a powerful strategy to follow and understand the structural changes of the studied lignins.Les modifications structurales de la lignines extraites de bois traités par autohydrolyse rapide ont été étudiées principalement en solution par les techniques de résonance magnétiques nucléaires. Les apports de la RMN du 13C quantitative, 2D INADEQUATE et des expériences DEPT ont été essentiels pour comprendre les analyses structurales des lignines étudiées

Suivi et catégorisation multi-objets par vision artificielle (Applications au suivi de personnes et de véhicules)

Cette thèse présente une méthode de suivi et de classification conjoints en temps réel d'un nombre variable d'objets tels que des piétons et/ou des véhicules, sous conditions d'illumination variables au cours du temps. La méthode retenue entre dans le champ du suivi Multi-Objets par Filtre Particulaire, dont la clé de voûte est l'échantillonnage des particules. Nous examinons deux familles de filtres particulaires : les Filtres Particulaires Partitionnés, et les Filtres Particulaires par Chaîne de Markov (FP MCMC). Nous comparons ensuite leurs performances sur des données de synthèse. Les résultats obtenus montrent la supériorité du Filtre Particulaire MCMC. Un système de suivi et classification conjoints en temps réel d'un nombre variable d'ojets tels que des piétons et/ ou des véhicules, sous illumination variable, est ensuite présenté. La mesure est délivrée par une ou plusieurs caméras statiques. Nous avons délibérément choisi d'alimenter le filtre avec une observation pauvre, reposant uniquement sur une segmentation binaire avant-plan / arrière-plan basée sur un modèle de l'arrière-plan mis à jour en ligne à chaque image. Pour résister aux variations d'illumination, les ombres sont modélisées et le filtre est étendu afin de suivre conjointement le soleil et les objets. Les résultats de suivi et classification en temps réel sont présentés et discutés sur des séquences réelles et sur des séquences de synthèse, impliquant plusieurs catégories d'utilisateurs tels que des piétons, des voitures, des camionettes et des poids lourdsCLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSudocFranceF

Fossil wood from the Miocene and Oligocene epoch: chemistry and morphology

International audienceFossil wood is the naturally preserved remain of the secondary xylem of plants that lived before the Holocene epoch. Typically, fossil wood is preserved as coalified or petrified and rarely as mummified tissue. The process of fossilization is very complex and it is still unknown why in the same fossil record, wood can be found in different fossilisation forms. In 2007, a fossil forest was found in the Bukkabrany open-pit coal mine in Hungary. The non-petrified forest is estimated to be 7 million years old (Miocene epoch) and its trees were found standing in an upright position. This fossil assemblage is exceptionally rare because wood has been preserved as soft waterlogged tissue. This study aimed to investigate this remarkable way of fossil wood preservation, by examining its chemistry with C-13 CPMAS NMR and its morphology with light and electron microscopy. For comparison reasons, a petrified wood trunk from the Oligocene epoch (30 Myr) found in 2001 at Porrentruy region in Switzerland and two fresh wood samples of the modern equivalents of the Miocene sample were also examined. The results obtained showed that the outstanding preservation state of the Miocene fossil is not owed to petrification or coalification. Mummification is a potential mechanism that could explain Bukkabrany trunks' condition, however this fossilisation process is not well studied and therefore this hypothesis needs to be further investigated. Copyright (c) 2014 John Wiley & Sons, Ltd